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The Recycled Generation

Almost every weekday morning, usually before 10:30, an overnight delivery truck with an unusual cargo negotiates the hilly streets on the outskirts of Worcester, Mass., and comes to a halt in front of a brick-and-tinted-glass building called Biotech Three. The courier disappears into the building with one or two large gray containers and drops them off at a small company called Advanced Cell Technology. The gray cases look like toolboxes, but they are actually sophisticated shipping containers, commonly used for transporting materials used in animal-breeding work, and they contain the starting material for a series of experiments that may completely rewrite the tables of human longevity. Or they may be remembered only for being among the most ethically troubling scientific endeavors of our times.

Inside the gray cases are hundreds of cow eggs -- big, plump and beautifully rotund oocytes, as they're technically known -- each one painstakingly plucked the day before from the ovaries of cows slaughtered in Iowa. They are doused with a marinade of enzymes that prime them for imminent fertilization and then sealed in small plastic test tubes before being shipped overnight to Worcester. On the drizzly, overcast day in mid-December when I visited the laboratories at Advanced Cell, the shipment of eggs arrived a little before me. In all the time that cows have roamed the planet, their oocytes have never encountered the insults they were about to face that day. The eggs would be stripped of their DNA, deliberately fused with human cells and fooled into thinking that fertilization had occurred, in the fervent commercial hope that some sort of an embryo might result.

Experimenting with embryos created from two different species -- to say nothing of engaging in a form of human cloning -- is an enterprise fraught with scientific and social uncertainty; indeed, Congress forbids the National Institutes of Health to finance any research involving human embryos. So it's natural to wonder why a small, largely unknown and understaffed biotech company would risk public scorn and ethical outrage to perform such research. One possible reason is publicity, which a number of critics have been eager to suggest. But the real answer, insists Michael D. West, the dreamy-eyed 46-year-old entrepreneur who heads A.C.T., is the scientific chase for what he calls ''the mother of all cells -- the embryonic stem cell.''

The embryonic stem cell is an almost mythically powerful and versatile human cell, fleetingly present during the earliest days of embryonal development. This one cell has the potential -- the genetic blueprint and the biological know-how -- to become any cell, any tissue, any organ in the human body. With the proper biochemical coaxing, for example, it can turn into heart muscle, which could replace tissue damaged by a heart attack. Or into brain cells, which could be used to treat Parkinson's disease. Or into retinal cells, which could be used to restore failing vision.

Imagine, in short, a cell so protean and potent that it could theoretically generate an infinite supply of replaceable body parts -- organ and skin, sinew and bone, blood and brain -- to knit the tatters of disease, injury or old age. Imagine further that, with the use of controversial technologies like cloning, you might one day donate a snippet of your own skin, allowing scientists to harvest stem cells that theoretically would become a self-generated and limitless supply of transplant tissue -- tissue that would make a perfect immunological match with you because, after all, it is you. These ideas have not only been imagined; patents and licensing agreements are already in place.

''These are incredible cells,'' gushes Thomas B. Okarma of Geron Corporation, the California biotechnology company that controls many of the patents and licenses on stem cells. ''I've been in biology since high school, and this is still a chilling technology when you see these things and realize what they do. The number of applications is mind-boggling.'' Last month, Science magazine dubbed stem-cell technology the ''breakthrough of the year.''

In spite of this promise, the scientific, commercial and ethical landscapes that intersect with these fascinating cells have been shaped, even turned upside down, by the right-to-life debate, because in order to obtain human embryonic stem cells by currently available technology, you must destroy a human embryo. Because of the Congressional ban on financing of this research, many scientists now find themselves in the awkward position of possibly losing their jobs if they try to use human stem cells to devise new treatments for many common diseases. ''With stem cells,'' says Ronald McKay, a researcher at the National Institute of Neurological Disorders and Stroke in Bethesda, ''you tickle them and they jump through hoops for you.'' McKay's group published a highly regarded paper in Science last summer showing how rat embryonic-stem cells could be used to treat a version of multiple sclerosis in rats, but he doesn't dare extend the research to test the method's effectiveness in humans. ''I would get fired if I did that,'' McKay says, fairly squirming in his seat to make this seem like the most reasonable thing in the world.

The ban on N.I.H. financing has also had the collateral effect of relegating the technology to the private sector, where embryo research can proceed unencumbered. But the fact that so much of this controversial research now occurs in the private sector means that public discussion has become constrained. And complicating this commercial landscape is the fact that two of the companies most avidly competing over the research, Geron and Advanced Cell Technology, have a tangled corporate history dating back to business opportunities created by the federal ban.

The common figure wandering through all these unsettled landscapes, popping up again and again like some white-coated Zelig is Michael West. West's insistence on pursuing controversial experiments in which cow eggs are used as cellular incubators in an attempt to create humanlike embryos comes at a particularly sensitive moment. Emboldened by a legal interpretation that seemed to show a way around the Congressional ban, the N.I.H. on Dec. 2 issued long-awaited guidelines explaining the rules by which the agency would finance human-stem-cell research. The 60-day comment period ends tomorrow, and the agency hopes to begin soliciting grant proposals from university researchers sometime this summer.

However, Representative Jay Dickey, a Republican from Arkansas who has blocked N.I.H. financing for embryo research since 1995, has already vowed to outlaw federally financed stem-cell research this spring, either through legislation or legal action. Senator Arlen Specter, meanwhile, who is entranced by the medical possibilities, has promised to introduce a bill explicitly allowing federal financing for the research.

West, whose laid-back, soft-spoken demeanor belies the soul of a headstrong provocateur, promises to be an impassioned voice in this debate, too. ''I think a lot of the problem we have in trying to develop these new technologies for medicine is people's knee-jerk reaction to words like 'fetal' and 'embryo,''' he says. ''You know, you use the word 'fetal' and people just go completely irrational.''

Until we learn how to direct the fate of human embryonic stem cells -- learn how to tell them, for example, that we'd like them to become a new liver or glistening white bone -- their enormous promise still remains under Nature's lock and key. Many scientists believe it will take at least 10 years before we learn how to program the development of cells that could be transplanted into humans, and probably many more before we learn how to coax stem cells into creating something as grand and complex as a liver or a kidney.

But let's say some version of the science will be in practice by the year 2011, when the first of the baby boomers turn 65. And let's say the technology of stem cells will be complemented by promissory notes redeemed in related fields of gerontological science. What might the menu of spare parts look like?

The first step in creating those spare parts (which could be used not only for the aged but also for anyone in need of intervention) might well be the donation by the patient of a biopsy sample, which could be quickly cloned, thus creating an early embryo, which would produce stem cells in a week or so. Every cell and every tissue derived from those stem cells would be a perfect immunological match, which would immediately circumvent the big stumbling block of current transplant medicine: matching tissue.

At that point, it simply becomes a matter of matching the ailment to the right cell type. Researchers speak of creating nerve cells to treat spinal-cord injuries, stroke and Alzheimer's disease; glial cells for multiple sclerosis; pancreatic islet cells to treat diabetes; muscle cells for muscular dystrophy; chondrocytes for arthritis; hepatocytes for cholesterol metabolism; endothelial vessels to grow new blood vessels to replace vessels clogged by fat and plaque -- there are more than 200 different cell types in the body, and stem cells can theoretically be nudged to form each one. If these cells are souped up, as has been proposed, with an enzyme that maintains its cellular youthfulness, we're talking not only about replacement parts, but also about parts that never grow old.

What might the world of stem-cell medicine look like? For one thing, every place in the developed world might look a lot more like Florida. Although the maximum attainable human life span is now approximately 120 years, only about 65,000 Americans have currently reached the age of 100. But a century from now, with new medical technologies in place, the Census Bureau predicts there will be 5.3million people living to the age of 100 and perhaps much longer. To hear the optimists talk, there'll be much longer waits for tennis courts and tee times.

This is the kind of speculation that keeps ethicists and philosophers busy, but there are a lot of touchier issues on the immediate horizon -- creating embryos for research purposes, combining biological material from different species and performing nuclear-transfer experiments involving adult human cells (also known as cloning). All three are being pursued in a single line of research at Advanced Cell Technology.

The experiments at A.C.T. take place in a long, dark, narrow room in the middle of the lab. The lights are kept low to allow technicians to view the cells through microscopes while poking, turning and prodding them with micromanipulation devices. K.C. Cunniff, her blond hair spilling out over a white lab coat, begins by vacuuming all of the cow's genetic material from the egg cells, one after another, for more than an hour.

As I watch a magnified view of the proceedings on a television monitor, it's hard not to be impressed by the nimble piecework of the technicians. Cunniff, 26, deftly maneuvers one pipette to hold a round, plump egg cell in place. (They prefer cow eggs because they are inexpensive and easier to use than either pig or primate oocytes). She turns the egg, which had previously been stained with a fluorescing dye, as if rotating a ball in her hand, until she sees a telltale blue-green speck of DNA. Using her other hand, she nudges a sharp, hollow needle up against the surface of the egg. With a precise thrust, she enters the egg, sucks out the DNA and withdraws the needle, all in a matter of seconds. ''Very quick,'' she says matter-of-factly. In, suction, out. Next egg. In, suction, out.

It's so matter-of-fact that you'd never guess this type of experiment was the focus of wildly fearful predictions only a few years ago. In 1997, when scientists at the Roslin Institute in Scotland announced the cloning of Dolly the sheep, there was a lot of fevered speculation about the possibility of cloning human beings. It was generally dismissed as both a distant and undesirable proposition, but the sudden appeal of embryonic stem cells has provided a surprisingly urgent medical justification for moving the technology of human cloning closer to reality.

In the case of A.C.T.'s experiments, the cow egg is being tested as a way to ''reprogram,'' or reset, the adult DNA back to a pristine state resembling the moment of fertilization. In these experiments, the egg comes from a cow but the adult DNA comes from human donors; it's the human DNA, West believes, that orchestrates subsequent embryonic development. The technical term for this type of experiment is ''nuclear transfer,'' but West prefers a more transparent phrase -- human therapeutic cloning.'' That modifier ''therapeutic'' signals that A.C.T. is not in the business of making babies, just embryos to get stem cells. And they're not alone in pursuing the nuclear-transfer approach. Last May, to remarkably little public comment, Geron acquired Roslin Bio-Med, the Scottish company in charge of commercializing the research that produced Dolly.

As Cunniff moves another cow egg into position, Nancy Sawyer gazes at the TV monitor and makes a sound like ''Unk!'' as the needle punctures the egg. ''That's so cool,'' she whispers of the image. Seen on the monitor, the image has a primal iconic beauty, like a dim grainy photograph of a distant planet. On each moonlike oocyte, one isolated lunar mare glows with an eerie greenish blue, betraying the location of genetic material that will soon be suctioned away.

At a nearby microscope, Sawyer, 24, performs the next step. Human skin cells, known as fibroblasts, have been provided by an anonymous donor. The human cells dot the screen like so many lumpy, transparent potatoes, much smaller than the egg cells. Sawyer loads them into a hollow needle, immobilizes a cow egg with suction and, with gentle pressure, inserts the needle tip just under the rind of the egg. With a squeeze of her hand, a single human skin cell, with its unique payload of human DNA, plops into the egg of a creature that moos. Sawyer even manages to maneuver her needle tip to literally tuck the hole closed.

After stuffing every cow egg with its little spud of human DNA, Sawyer prepares the next step. She gives the cells a zap of 120 volts. The jolt of electricity effectively fuses man and beast into a single biological fate. After one final step, this . . . this thing will believe it has been fertilized and, if all goes well, begin cleaving, or dividing, in the bubbling, momentous arithmetic of life lifting off the pad: 2 cells, 4 cells, 8 cells, 16 cells, 32 cells -- blastocyst!

The odds are extremely long that any of the 100 or so cell fusions will result in a blastocyst, the hollow ball of cells that appear about a week after fertilization and, in a normal embryo, are destined to become the placenta. But if that ball of cells should form, a separate group of cells known as the inner cell mass assembles against one inside wall of the blastocyst, like bats huddling on the ceiling of a cave, and this is where the embryonic stem cells will appear. These stem cells exist only briefly before they begin to differentiate into more specialized tissues -- there one moment and gone the next, transients vanishing into the great biology of becoming. ''If I'm lucky,'' says Jose Cibelli, vice president of research at A.C.T., ''I'll get one blastocyst. That's how low the efficiency is.'' And getting the blastocyst is just the first hurdle -- can they isolate the stem cells and keep them alive in a test tube? And will they truly act like human embryonic stem cells?

Before leaving Worcester that day, I ask Cibelli when he will know if any blastocysts have formed from the experiment I've observed. He says he wouldn't expect to see anything before 9 or 10 days. I do the math in my head and make a mental note to get in touch either on December 24 or Christmas Day.

In many ways Michael West is the shadow impresario of the field. As founder of Geron Corporation, one of this decade's most closely watched biotechnology companies, and now as president and C.E.O. of Advanced Cell Technology, West has achieved remarkable success as a kind of merchant of immortality, selling the idea that stem cells and related technologies might someday completely revise the tables of average human life span. And he is so convinced that the promise of stem cells justifies a controversial strategy like cow-human nuclear transfer that he is happy to foster, if not force, a national discussion of this technology.

In a recent issue of the journal Nature Medicine, for example, West, Cibelli and their colleague Robert Lanza argued the case for human therapeutic cloning because stem-cell research is so promising. ''Does a blastocyst,'' they wrote, ''warrant the same rights and reverence as that accorded a living soul -- a parent, a child or a partner -- who might die because we failed to move the moral line?'' And that is what Mike West is trying to do at this touchy juncture of the stem-cell wars -- with this company, in these experiments, in an ethical debate that has seemed too arcane and complicated to attract much public attention to date. He is putting his shoulder to the moral line that forbids embryo research and is trying to force some sort of social reckoning. The degree to which he and others succeed or fail may well determine if stem cells have a chance to live up to their promise as medicine or remain too hot to handle in the current political climate.

Stem cells burst into public consciousness little more than a year ago. In November 1998, James Thomson of the University of Wisconsin reported the creation of human embryonic stem (or E.S.) cell lines. Using leftover frozen embryos from in-vitro fertilization clinics in Wisconsin and Israel, Thomson and colleagues isolated stem cells and have shown that they can be maintained indefinitely in the lab -- can be grown, frozen and then thawed, and still retain their power to develop into, say, heart-muscle cells or brain cells. Michael Shamblott and John Gearhart, at the Johns Hopkins School of Medicine, headed a separate effort to cultivate something called ''embryonic germline'' (E.G.) cells, which are harvested from a tiny speck of fetal tissue from an aborted fetus and then grown in the lab. Because of the Congressional ban on federal financing for human-embryo experimentation, both teams conducted the research with financing from Geron.

There are many technical hurdles to overcome. But the sheer power of the approach makes it clear that, if properly harnessed, stem cells could serve as a warehouse of spare human parts. This teasing hint of immortality is the cultural subtext that runs beneath the public fascination with the science, and no one has done more to promote that connection than West. The son of a truck mechanic, West is a onetime creationist and a self-styled truth seeker, and his entrepreneurial interest in the biology of aging derives from an obsessive, almost morbid fascination with death. ''All I think about, all day long, every day, is human mortality and our own aging,'' he says.

The first time I visited Advanced Cell Technology, West showed up two hours late for our appointment, apologized with sheepish charm for his tardiness and began to spin out the kind of polished futurism he regularly conveys to scientists, investors and lay people. ''I thought I'd show you some pictures,'' he said, and then proceeded to project slides on a screen in the company's conference room, delivering a lecture on the biology of aging to an audience of one. With his gently soothing Midwestern voice and relentlessly upbeat brand of biological positivism, he manages to make science sound almost like a cult. Former colleagues concede that he does not possess a crisp management style (punctuality, for example, being a continuing challenge), but even his critics admit he has a knack for looking beyond the horizon and dreaming deep. He'll talk for hours about saving endangered species through cloning, or the possibility of cloning pets, or why it makes more economic and ethical sense to pay $1 for a cow egg than $2,000 to surgically obtain a single human egg. ''He's a very visionary guy,'' says James Thomson, a University of Wisconsin biologist, ''but he's also a very good salesman.''

Even as a high-school student growing up in Niles, Mich., West was fascinated with aging and rejuvenation. He immersed himself in religion and philosophy. He learned Hebrew and Greek, he says, to read ancient texts in the original. He went on to study psychology at Rensselaer Polytechnic Institute, obtained a Masters of Science degree at Andrews University, a Seventh-day Adventist school, and even studied creationism for a time in San Diego, he says, before convincing himself of the truth of Darwinian evolution. Following the death of his father in 1980, West worked in the family's truck-leasing business and then belatedly embarked on a career in science. He received his Ph.D. in cell biology from the Baylor College of Medicine in 1989 and started medical school at the University of Texas Southwestern Medical Center in Dallas.

That same year, West showed up unannounced and began to hang out at the University of Texas lab of Woodring Wright and Jerry Shay, who were researching the molecular biology of aging. Four years earlier, scientists had discovered a critically important enzyme called telomerase, which acts on telomeres, the little caps of DNA at the end of chromosomes; telomeres ordinarily grow shorter each time a cell divides, until the cells stop dividing altogether. It turned out that a handful of human cells -- germ cells, cancer cells and embryonic stem cells -- use telomerase to circumvent that shortening process, and thus also circumvent the aging process and achieve a cellular version of immortality.

As West learned more about telomeres, he eventually came to view the enzyme telomerase as a molecular version of the fountain of youth; it looked as if it might bestow immortality on normal cells and, conversely, could have the beneficial effect of pulling the plug on immortality in cancer cells if blocked. While still technically enrolled in medical school, West moved out to California and banged on doors in search of seed money for a biotech startup. Thus, in November 1990, he founded a company dedicated to the molecular causes of aging. He named it Geron -- Greek for ''old person.'' He eventually captured the interest of the most prestigious venture-capital firm on the West Coast, Kleiner Perkins Caufield & Byers, which along with other firms invested $7.6 million in Geron in 1992.

For a company that has lost tens of millions of dollars and is in no danger of curing aging anytime soon, Geron has managed to cast a spell on investors, the media and the lay public. In both technical articles and news releases, it has retailed a scientific vision (and vocabulary) that clearly push the right zeitgeist buttons. West and Geron spoke tirelessly of ''immortalizing enzymes'' and the ''life extension'' of cells; Geron is almost universally recognized as an ''anti-aging'' company. And in 1997, after winning a highly competitive race to clone (and patent) the human gene for telomerase, Geron actually had a real molecule around which to develop clinical products. The company currently has a number of promising directions for telomerase-based products, including potential anticancer applications, but the mythology is so firmly established that even though company officials insist Geron is no longer an ''anti-aging company,'' this is still how it is inevitably portrayed.

From the very beginning, however, West had another big idea he wanted to pursue. ''You need replaceable cells and tissues for the problems of aging as well,'' he said. ''And it seemed to me that the ideal source for an aging population is to go back to the beginning of life.'' To the embryo, that is, and stem cells. And so, as early as 1992, he paid a visit to Roger Pedersen, a professor of obstetrics, gynecology and reproductive sciences at the University of California at San Francisco, and a leading expert on embryonic stem cells in mice. They both agreed that the time had arrived to explore the vast potential of such embryonic stem cells in human medicine, and West inquired into whether Pedersen would accept financing from Geron to do research on human stem cells.

Pedersen flatly refused: ''This area of investigation is something that is at the headwaters, and it's not appropriate for private investors to control the headwaters of a stream of research.''

Several years later, however, Pedersen got back in touch with West. Circumstances had changed, he said, and he was ready to deal.

The circumstances were political. In 1975, federal regulations stipulated that any government support for in-vitro-fertilization research required the approval of a federal ethics advisory board. After a short and turbulent history, this board was disbanded in 1980 without a single research project having received government funds. One cynical stratagem of the Reagan and Bush administrations, according to Pedersen, was to block all attempts to reconstitute the panel, effectively thwarting such research throughout the 1980's.

Under the new Clinton administration, Congress did away with the phantom federal ethics review and set up a special N.I.H. committee to establish guidelines for human-embryo research. Everything seemed back on track when, early in 1995, Jay Dickey, the Republican congressman from Arkansas, successfully inserted a rider into the budget bill for the Department of Health and Human Services (which includes the N.I.H.) banning federal funds for human embryo research. Just as right-to-life politics had forced in-vitro fertilization and reproductive biology into the private sector, where lack of oversight and regulation has led to a series of well-documented scandals, stem-cell research seemed headed for similar privatization.

Those were the circumstances that had changed Roger Pedersen's mind. Geron reached an agreement with the University of California to finance Pedersen's work on embryonic stem cells. During his discussions with West, Pedersen mentioned that a scientist at the University of Wisconsin, James Thomson, was about to publish a paper announcing another breakthrough: the isolation of embryonic stem cells from rhesus monkeys. West was in Wisconsin the next day, and Geron signed up Thomson too.

''I would have been much happier with public support,'' Thomson admits. ''But given the constraints, I welcomed the funding I got.'' Getting access to stem cells from a primate, an animal biologically close to humans, West realized, promised tremendous intellectual-property dividends. ''We could just learn how to work with them, and file patents,'' he said. ''But we'd have this head start on the whole world.'' When West later learned that another university researcher, John Gearhart at Johns Hopkins, had made significant progress isolating cells very similar to embryonic stem cells, he headed straight for Baltimore. ''He just showed up on my doorstep one day,'' Gearhart recalled with a laugh.

With Pedersen acting as talent scout, West chased down and signed up three of the leading stem-cell researchers in the world. Geron began to assemble a staggering intellectual-property portfolio in a field with almost limitless medical potential. And because the Congressional right-to-life advocates had effectively tied the N.I.H.'s hands in terms of financing, there wasn't any competing research in university labs. The investment paid off spectacularly in November 1998, when both Thomson and Gearhart announced they had isolated human stem cells. The universities where the work was done retained the patents on the research, but Geron received exclusive rights to many applications.

Unfortunately, Mike West enjoyed this moment of triumph only vicariously, because by then he had left the company, unhappily. In 1997, according to several sources, Geron planned to spin off its entire stem-cell program into a separate company, which would include West, when the plan, in the words of a scientific board member of the company, ''got clobbered by the company leadership.'' Thomas Okarma, who joined Geron in December 1997 and is now president, offers a different interpretation. ''I was hired explicitly to run that program because it really wasn't moving,'' he said. In any event, the stem-cell research stayed at Geron, and West says he increasingly felt he could do more outside the confines of the company than inside.

The fact that West's current company, Advanced Cell Technology, is now competing against the company he founded may go a long way toward explaining why Mike West is so determined to find an alternative way of obtaining human stem cells, one that doesn't rely on existing human embryos in clinics or fetal material from abortions -- the methods that Wisconsin and Johns Hopkins licensed to Geron. And it certainly explains why he perked up when, a few months after leaving Geron, he learned of an unusual experiment by Jose Cibelli, an Argentinian scientist working at Advanced Cell Technology. The good news was that Cibelli had tried to isolate human stem cells using a method that seemed to offer an alternative to Geron's approach. The bad news was that the strategy involved human cloning. And cows. ''And I knew,'' West says, ''that was going to be a problem.''

In the summer of 1996, Cibelli was a graduate student at the University of Massachusetts at Amherst, working in the laboratory of James Robl, a respected developmental biologist. Cibelli had the radical idea of fusing some of his own cells with cow egg cells, in effect cloning himself -- not to make a copy, of course, but as a way to get human stem cells. Interestingly, this wasn't the first time Robl had been confronted with such an idea. Several years earlier, a student in the lab, unbeknown to Robl, had fused human cells with the egg cells of a rabbit, and the cells had begun to divide. This time, Robl went to university officials and received institutional approval to proceed.

During July and August, Cibelli rinsed out some of the cells that lined the inside of his cheeks and tried fusing them with cow egg cells. ''One day, Jose was about to go on vacation, and he was about to throw out the dish,'' Robl recalls. ''I don't generally look at these things, but I did that day. And there was a blastocyst.'' In other words, the embryolike thing had moved beyond mere cell division and graduated to the stage where embryonic stem cells begin to form. As is routine when the experiment reaches this stage, Cibelli placed the fragile blastocyst on a bed of fetal mouse cells, which nourished its further development. ''We watched it for about two more weeks,'' Robl says. ''It looked, to my eye, not like a cow blastocyst. The morphology of the cells was different.''

Cibelli and Robl did not publicly discuss the experiment at the time, nor did they prepare a scientific report for peer review. ''We never considered a publication,'' Robl explains, ''because there was not nearly sufficient data.'' But the University of Massachusetts did consider the experiment sufficiently novel to file a patent application. The United States patent was issued, virtually unnoticed, last August.

Cibelli recounted this remarkable story to West in the spring of 1998, when West happened to be visiting A.C.T. ''I was just flabbergasted,'' West recalls. ''I mean, he showed me human embryos that had been made by cloning. And I had no idea -- no one in the world had any idea -- that it had been done. I thought, 'Oh my gosh, this is exactly what I want to be doing for the next 10 or 20 years of my life.''' More to the point, it was exactly the kind of technology that would allow him to get back into the stem-cell game.

West officially joined A.C.T. in October 1998 and immediately presided over an episode that was, for him, uncharacteristic -- a major public-relations fiasco. As soon as West joined the company, Cibelli lobbied to resume his cloning experiments. West agreed, but wanted to disclose details of the 1996 experiment and gauge public reaction to the technology before starting it up again. ''I didn't want to be accused of doing this in secret,'' he says. So he invited a film crew from the CBS newsmagazine ''48 Hours'' to film the work in progress.

Then, one week before the scheduled broadcast, on Nov. 6, West got blindsided by his previous life. Geron announced Thomson and Gearhart's successes isolating stem cells. ''I had no idea it was coming,'' West admitted. It wasn't just that the research made front-page headlines and drove Geron stock up 74 percent in one day. By the time CBS broadcast the show on Nov. 12, along with a news account of the experiments that appeared in that morning's New York Times, West's professed desire for openness looked like something entirely different: a bid to leverage ''me too'' publicity for his otherwise unknown company.

For an experiment that never received formal peer review, Cibelli's cow-human nuclear-transfer work got plenty of unofficial feedback, beginning with the White House. Clinton called it ''deeply troubling.'' Thomas Murray, president of the Hastings Center and a leading bioethicist, wondered ''if the timing of the announcement had to do with scientific competition, personal competition or positioning for funding from investors.'' Roger Pedersen was quoted as saying, ''I smell a sham.'' (He claims he wasn't told who performed the experiment when he was asked to comment upon it.) Thomson regarded the whole affair as ''unfortunate.'' Right-to-life pickets showed up outside Biotech Three in Worcester, marching around in cow masks.

Two days after news of the cow-human experiments broke, President Clinton asked his National Bioethics Advisory Commission to prepare a report on stem-cell research in general. The commission hastily convened hearings in January 1999 in Washington. And who should turn up, uninvited, to make an unscheduled presentation before the panel but Michael West.

'I read an editorial by an individual who wrote that science should stop so that ethics can catch up,'' West told the national commission that day. His ambition, he said, was ''to communicate to people in public policy and in biomedical ethics, so that, simply, ethics can walk hand in hand with science.'' Ethics and modern biology, however, have rarely walked hand in hand, and stem-cell research has added new difficulties to the relationship.

Over the past year, two high-powered advisory committees have, with one significant difference, endorsed the general idea of embryonic-stem-cell research. A committee established by the American Association for the Advancement of Science recommended last August that researchers be able to receive public funds for experiments on embryonic stem cells, but only using cell lines already created by researchers in the private sector. The National Bioethics Advisory Commission, by contrast, recommended last September that researchers financed by the N.I.H. should be allowed to create stem cells using human embryos already in existence (thousands of such embryos, frozen and destined to be discarded, exist at in-vitro fertilization clinics).

But no oversight or guidelines exist for private industry, and in February 1999, well before either committee delivered its opinion, Advanced Cell Technology quietly decided to resume its cow-human nuclear-transfer experiments. It seemed like an important decision for such socially sensitive research, so I asked West if it was something that went to the board or an ethics advisory panel for approval. West said it was strictly his decision. And there's the paradox. Now that abortion politics has forced so much of the research into the private sector, the transparency of the ethical conversation about it has become more obscured.

Everyone, including Mike West, insists on an open national debate about stem-cell research. But I began to notice that whenever I asked one question too many about exactly what work was being done, or even contemplated, the conversations became elliptical and vague. I was having lunch with West one day, for example, when I asked if the use of human donor eggs for cloning experiments was under consideration. Cibelli had told me he thought such a development was very likely. ''I have to confer on this issue,'' West replied apologetically, leaning over to huddle with A.C.T.'s public-relations adviser. Then, after a pause but without directly answering the question, he expressed concern that such a program could exploit women.

For all their good intentions, ethicists may have allowed themselves to be placed in a difficult, possibly untenable position. At Geron, for instance, the company's ethics advisory board seems to have the ear of management. But, says Karen Lebacqz, who heads the Geron ethics advisory board, ''they are perfectly at liberty to ignore all our advice.'' Further, as Lebacqz points out, she is not free to discuss certain aspects of the research. ''Early last summer, they brought us a piece of research that they were going to fund. Several members of the board raised objections, so they decided not to pursue that particular line of research.'' What was the research under discussion? ''I'm sorry, I really can't,'' she said.

The ethicists have become proxies for all of us, precisely because so much of this technology, for political reasons, is unfolding in the private sector. Yet they have limited power. West, for example, told me that when Geron first considered establishing an ethics board, the company determined that giving such a board the right to veto research projects would undermine its fiduciary responsibilities to shareholders. The ethicists have what West calls ''the power of the pen,'' but what they can report back to us is constrained.

Their mere participation in the process, however, creates the appearance of oversight and ethical responsibility, and that is precisely what bothers David Cox, vice chairman of the genetics department at Stanford University and a member of the national bioethics commission. Cox says ethics advisory boards at biotech companies are ''a joke'': ''They're supposedly doing ethical review, but the process by which they're working is backwards.''

It's very hard to have a national debate on issues as socially and ethically important as cloning and the creation of embryonic stem cells when every conversation may ultimately bump up against corporate confidentiality. The problem of openness is compounded by the editorial policy at a number of leading scientific journals, which refuse to publish research if the results have previously been disclosed in public. That almost guarantees that breakthroughs in a controversial and competitive field of research like stem cells will land in the public's lap as scientific faits accomplis, just as Dolly did.

And it leaves us in the same scientifically uncertain and ethically queasy place we were more than a year ago. At that time, Thomas Murray of the national bioethics commission asked West if he thought the cow-human experiments resulted in human embryos that were potentially ''viable'' -- in other words, embryos that, if implanted in a woman, could result in a live human being. West didn't answer, and A.C.T. still isn't answering. I asked Jose Cibelli, for example, if the A.C.T. scientists had made any progress overcoming the problem of biological incompatibility between a cow egg and a human cell, an issue involving small cellular organs called mitochondria; it is an obstacle repeatedly raised by the many scientists who remain skeptical about the approach and are dubious that a blastocyst would be created, especially since A.C.T. still hasn't published a sprig of data on it in more than a year.

''We think,'' Cibelli began to say, ''but this is very preliminary. . . . '' He shrugged and smiled. ''You can say that we've had good progress,'' he continued with a little laugh. ''We've had good progress, and we expect to have something to report in the near future. But I guess I need to be protective of the data for publication's sake.''

Michael West sounded a similar theme when I told him how many complaints I'd heard about A.C.T's unpublished experiments. ''We could publish now, the data we have,'' West assured me, well aware of the exasperation of the research community. ''But,'' he continued, ''we're trying to generate a real killer paper here. We're going to do a paper we're proud of.''

On Christmas Eve, I sent an e-mail to Jose Cibelli, asking about the status of the cells I'd seen fused. The day after Christmas he wrote back to report that the nuclear-transfer units had ''developed at the 'predictable' rate,'' while declining to specify exactly what that was. As soon as new techniques were in place, he continued, Advanced Cell Technology would report the results in a peer-reviewed journal.

As congress prepares to debate the merits of stem-cell research in the coming months, we will undoubtedly hear rosy visions of the future of medicine with stem cells (as well as the contorted political logic that suggests that research on human embryos and cross-species nuclear-transfer experiments are permissible in the private sector, but morally indefensible in the public sector). But it's also worth thinking through the implications of immortalizing medicines, which I had the opportunity to do with Leonard Hayflick, the elder statesman (and elder contrarian) of the field.

Hayflick, now 71, is a well-known cell biologist; his discovery in 1961 that normal human cells grown in a test tube simply stop dividing after a specific number of cell divisions, known as the Hayflick limit, in effect introduced the notion of mortality into the biology of aging. We arranged to meet at the Union Club in Manhattan in early December, when Hayflick showed up to harangue fellow board members of the American Federation for Aging Research about their financing priorities.

Hayflick doubts we'll ever have a quick fix to arrest aging anytime soon, but he has lots of reasons to think it would be a very bad idea. Like a number of bioethicists, he believes the first line of division is economic. Access to the regenerative medicine of stem-cell and immortalizing enzymes is most likely to be a phenomenon available only to affluent segments of the population in the developed world.

In his book ''How and Why We Age'' and other writings, Hayflick has even gone to the trouble of imagining ''bizarre situations'' that might unfold if scientists were ultimately able to create a medication that would, from the moment treatment began, essentially freeze the process of aging at a certain point. He has imagined ''children becoming biologically older than their parents'' if a parent chose to stop aging at age 45, for example, while a child did nothing. How would you even know, he asks, the right age to stop at?

Karen Lebacqz has also pondered this distant future. ''If we are successful with the use of stem cells or in the reprogramming of cells,'' she says, ''it will mean that people are no longer dying of the things we are dying of today. What do we do with all of ourselves if we don't die?'' We'll squander even more of the world's resources, she continues, and put even more pressure on the developing world.

But perhaps the ultimate argument against the implicit promise of immortality has to do with a simple biological fact: if we were to rejuvenate our brains, Hayflick argues, we might lose the most precious thing we have: our sense of self. ''Given the possibility that we could replace all our parts, including our brain, then you lose your self-identity, your self-recognition. You lose who you are! You are who you are because of your memory.''

There is a lot of scientific research and a lot of heated political debate to come before we arrive at any of those distant quandaries. And how we resolve the ethical conversations we're in the midst of having over stem cells will have a lot to say about whether we'll have a chance of reaching that future at all.